How do I connect two Ethernet Networks

I have an existing ethernet home network with a number of XP PC's and a Netgear Dg834GT Broadband router. For a development project I have want to link another small network configured as different sub-net with a number of devices on it.

I believe I need another router (or possibly a gateway) to link the two ethernet networks. The problem is there many available routers on the market, most of which have are ADSL - Ethernet ports. I need Ethernet - Ethernet ports. I see there are some Routers available with say 4 10/100 ethernet ports and another WAN Ethernet port for connection to an ADSL or Cable Modem. Will this type of router work for me if I connect the WAN port to my existing network and use the other ethernet ports for my new network ?

If not can anyone recommend the type of router I need to look for, examples would be good ?

a WAN port is fine. So long as it's the RJ-45 port that Ethernet needs, you'll be OK. Router manufacturers name the port lots of different things, but so long as the routers aren't in the same subnet (looks like you got that part under control), then you should be able to hook them straight together.

I had some success doing this. I got hold of an old Netgear RP114 Cable Modem Router. However the NAT built into the device seems to causing some restrictions. This is what I have :-
Net 1 (192.168.1.x) has broadband router (DG834GT) at 192.168.1.1 the WAN Port of the RP114 is attached to the switch on this net. I have fixed the IP of the WAN port as 192.168.1.128 in the DHCP server of the DG834GT), No Problems.
Net 2 (192.168.0.x) is all on the LAN side of the RP114. A pc on the 0.x net can access the internet or any pc on the 1.x net via ping or pcAnywhere or whatever. HOwever access the otherway round can only be achived by configuring the port forwarding in the RP114. Thus to connect pcAnywhere from PC 192.168.1.2 to a PC 192.168.0.2 on the LAN side of the RP114 I actualy have to connect to 192.168.1.128. ie 192.168.1.128 is a sort of spoof of whole network on the LAN side of the RP114. This what NAT is supposed to do.

Is there anyway of turning off the NAT in the RP114 (I can telnet into the embeded unix shell). Or is there a different type of router I should be looking for ? ie Will a VPN router help me ?

Man, you're really overcomplicating things. Maybe it's because you didn't tell what all you were doing on this network.

Why do you need seperate subnets, anyways? The machines on the .0.x network are going to be a pain to get working at all with port forwarding. I had assumed since these are on a seperate subnet, you wouldn't need to access them.

If you need to access them, why not set up a bridge, and put the machines on the same subnet? Or, if you're using Windows XP, you can assign 2 IP addresses. The machines that need to access the "experimental" network can simply have 2 IP addresses, and access anything they want.

What is your goal with the two disparate networks? Are you trying to limit broadcasting, or conserve main LAN bandwidth? The only way to do without NAT is to implement a router like a Linux/BSD box, and set static routes to the experimental network. That, though, would mean that you'd have to figure out how to get the other LAN hosts to recognize that gateway. You can do that through the Advanced TCP/IP properties of an adapter in Windows XP/2k, or you can use the route command to statically set one in Linux.